Still carb troubles

[billdn]

Back in February I posted saying I think I'd sorted my troubles with carbs not shutting down . In April I went for a Boyer electronic ignition complete with micro coils and I still have the same problem with the carbs !
There's quite a long time between posts because my wife was very ill with lung cancer and sadly passed on 30th June , so shed time was the last thing on my mind!
However one of her last wishes was "Get that bl##dy bike sorted!"  So I'm now back in the mood to try and sort it.

From the top :-
Boyer fitted and bike starts/runs. Using a timing light its correct.
Tappets adjusted.
Have to fiddle with idle adjuster to set at 1200rpm .
Idle mixture screw set at 2 turns out.
Plugs very sooty
Open throttle and revs soar and doesn't drop back to 1200rpm when released. Have to fiddle with idle adjuster to bring back down.
Sprayed carb manifold connectors to barrels with Carb cleaner and no effect , so not drawing in air, better not they're new - good
Remove carb tops and sprayed carb cleaner in but slides don't appear to be sticking either.
I've noticed that if you press the top of brass hexagonal nut on the carbs this will reduce the revs but too hard and it stalls FWIW.
Prior all carbs stripped, ultrasonic cleaned, carb cleaner on jets with jet brushes etc etc retaining original brass and new seals from NJ.
Bench synced at least twice.
Standard air box and new air filter

I've no idea what to do next! I have an old lawn mower, never serviced, starts first time every spring,  think I'll put engine from that in instead.

To me it's pretty obviously  carb related, (I think  ) as there is good spark and timing is ok. Not got to the stage with setting Boyer to full advance  yet which requires 4500rpm as revs all over the place.
Cheers peeps!

[Nurse Julie]

So very sorry to hear of your loss Bill 😢😢😢
Also so sorry to hear you're still battling the carb gremlins 😁😁😁😁

[Oddjob]

Very sorry to hear about the wife.

You could try this as to me it sounds as though the throttle lifters are set too high, especially if the carbs have been apart.

Get the adjuster screws, the ones with the little 8mm headed nuts on and the flat bladed screwdriver slot. Screw them all down as far as they can go. You may now struggle to get the bike to tickover and starting will involve a little jiggling with the throttle. Once you get it started adjust the main tickover screw to see if it will idle. If so, now vac the carbs to equalise them.

See if that works.

Before you do that post a pic of the adjusters so we can see how high they are now.

[Matt_Harrington]

Bill, sorry to hear about your wife......

As Ken says, the adjusting of the lifters can have a remarkable affect on the tickover and settling back to idle.

[royhall]

Sorry for your loss Bill.

That sounds to me like the quadrant is not positioned correctly when it was reassembled. Got the tee shirt for that one, took me ages to find it but the symptoms were as described above. Repositioned things correctly and it was spot on. Unfortunately the old memory won't allow me to remember how I fixed it but someone will know.

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[McCabe-Thiele (Ted)]

Sorry again to hear about Rose, good to read you are taking her advice & cracking on with the 400.

Can't remember without trawling through your old posts if you did a bench sync or not.
It was beginners luck with my 400 as I did the bench sync after rebuilding the carbs I think it's called to get all the sliders equal iirc I used a 1/8" drill bit shaft to get them all the same.

The below links I found very handy as well as the video & tips here.



.https://www.vintagebikebuilder.com/cb350-400f-carb-rebuild-demonstration.html

https://www.youtube.com/watch?v=JFTOfYl5BSc



 

[philward]

Can't help with the carbs Bill but so sorry to hear about your loss and hope you get her wish sorted!

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[Multiman]

So sorry to hear of your loss.
But heartened to hear you are pressing on with getting the 400 sorted.
If the advice above doesn't work my similar problems were sorted when I got the correct brass in all the carbs.
Best wishes
Tim

[Bryanj]

Bill, sounds like the bench sync wasnt quite right, i had the same problem with the 400 carb jigsaw i had for a member on here, what Ken suggested is a good idea, if you can get them off, undo the tickover screw all the way then unadjust all yhe little adjusters till you are certain all the slides bottom out, pick one to use as set point and lock small adjuster then using big tickover screw adjust till smallest, undamaged, drill shank, idealy 1mm, just slides under flat side of throttle slide(engine side) the adjust all small adjusters so all slides are same using the drill as a feeler gauge.
If you had them totally apart check you havent mixed the slides up as they are handed and you would not be the first to make that mistake mate.
Condolances on your wife and we will do all we can to get that *^##*^bike sorted

[billdn]

Sorry for your loss Bill.

That sounds to me like the quadrant is not positioned correctly when it was reassembled. Got the tee shirt for that one, took me ages to find it but the symptoms were as described above. Repositioned things correctly and it was spot on. Unfortunately the old memory won't allow me to remember how I fixed it but someone will know.

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Thanks Roy,
Not sure what you mean by the quadrant ? Do you mean the part the the push/pull throttle cables connect to? not sure how that could be misaligned but every day is a school day with this.
Cheers
Bill

[billdn]

Thanks all for the thoughts and support, it's been a rough road .
but inwards and onwards!
I'll try Ken's suggestion first and then if needs be, and fear it will , I'll take off the carbs, again and do yet another bench sync. The guy on the production line building the 400 must have loved his job of fitting the carbs !
Might be a day or two as got to help the oldies (parents) for a few days after today.
But as Arnie says "I'll be back"

[Johnny4428]

So sorry for your loss too Bill! But power to your elbow for stepping out the other side and getting on with things! Good to have a focus and distraction. Good luck with the running issues.

[royhall]

I will go back and check my 350F build thread when I get a chance. My carbs came ready built from Gerben in Holland and came with the quadrant problem. He sent me an email of how to rectify it so will look for that as well. Yes the quadrant is where the push and pull cables connect. Is your pull cable only just fitting or is there plenty of adjustment.

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[billdn]

Very sorry to hear about the wife.

You could try this as to me it sounds as though the throttle lifters are set too high, especially if the carbs have been apart.

Get the adjuster screws, the ones with the little 8mm headed nuts on and the flat bladed screwdriver slot. Screw them all down as far as they can go. You may now struggle to get the bike to tickover and starting will involve a little jiggling with the throttle. Once you get it started adjust the main tickover screw to see if it will idle. If so, now vac the carbs to equalise them.

See if that works.

Before you do that post a pic of the adjusters so we can see how high they are now.

Pics of adjusters prior too screwing in , hopefully attached

[billdn]

I will go back and check my 350F build thread when I get a chance. My carbs came ready built from Gerben in Holland and came with the quadrant problem. He sent me an email of how to rectify it so will look for that as well. Yes the quadrant is where the push and pull cables connect. Is your pull cable only just fitting or is there plenty of adjustment.

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Cables fine Roy, plenty of adjustment on both, which I think is good 😏